Iran on Sunday launched a new warning against any attack on its nuclear sites, amid reports Israel and the U.S. mull the possibility of a military option to stop Iran's nuclear program if diplomacy fails. The Iranian Supreme Leader Ali Khamenei, warned Sunday that any attack by Israel against its nuclear sites "will fall like a thunderbolt" on the head of the Jewish state, accusing the West of "lying" about the Iranian nuclear threat.

Israeli and American officials have begun to discuss the possibility of military strikes against Iran's nuclear program since the collapse of negotiations in Baghdad between the major powers and Iran last month. "All options are on the table", reiterated Wednesday the Israeli Defense Minister Ehud Barak in an allusion to a possible attack against Iran. "We must find the right time before it is possible to act".

On his part, the U.S. ambassador to Israel, Dan Shapiro, said his country had "no intention to continue discussions indefinitely" and that "the window is beginning to close" in front of a diplomatic solution.

"If the Zionist leaders talk of military action (against Iran), it is because they are (...) more vulnerable than ever. Any wrong decision (...) will fall on their head as the lightning, "stated Ayatollah Khamenei in a speech to mark the 23rd death anniversary of Imam Khomeini, founder of the Islamic Republic.

His chief military adviser, former commander of the Revolutionary Guards Yahya Rahim Safavi, warned on Saturday that Tehran would respond militarily to any attack. He reiterated that Israeli and U.S. bases in the Middle East as well as the U.S. Fifth Fleet in the Gulf were within range of the large arsenal of Iranian missiles.

General Rahim Safavi, however, chances of an attack by Israel or the United States were "slim."